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Limiting global warming

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A pressing question from the recently concluded 29th annual United Nations Climate Change Conference in Azerbaijan is how to transition away from fossil fuels and speed up climate mitigation in line with the 1.5 °C global warming target.

Keeping global average temperatures below 1.5 °C above pre-industrial levels is crucial to avoid the most severe impacts of climate change, including extreme weather, rising seas, biodiversity loss, and disruptions to food and water security. 

According to a new study by researchers from Stockholm University, Chalmers University of Technology, and Uppsala University in Sweden, it is still possible to limit global warming to 1.5 °C.  But the study found that the United States, the European Union, and 16 other countries will have to exceed their own current targets in order to achieve this global goal.  

The study, which was recently published in the journal Nature Communications, introduced an “additional carbon accountability” indicator, which quantifies countries’ responsibility for mitigation and carbon dioxide removal in addition to achieving their own targets.

The study identified 18 countries that should be accountable for increasing their ambitions to stay within their equal per capita share of the global carbon budget for 1.5 °C.  Additional carbon accountability is highest for the United States and China, and highest per capita for the United Arab Emirates, Russia, Saudi Arabia, and the U.S.

Failure to limit global warming risks catastrophic impacts of climate change.

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COP29: Possible to limit climate change to 1.5°C – if EU and 17 other countries go beyond their own targets

Photo, posted December 27, 2015, courtesy of Gerry Machen via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Electric vehicles and health

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Much of the discussion about the benefits of electric vehicles centers about the climate impact of not burning fossil fuels as well as about reduced operating costs.  A new study by the University of Toronto looked at the health benefits of large-scale adoption of electric vehicles.

The Toronto researchers used computer simulations to show that widespread electrification of the U.S. vehicle fleet when coupled with significant use of renewable energy to power the fleet could result in health benefits worth between $84 and $188 billion dollars by 2050.  Expressing these benefits in dollar terms is a way to quantify those benefits, but clearly what is most important is people’s health.

Carbon dioxide coming out of tailpipes is what is most harmful to the climate, but there is much more than CO2 vehicle exhaust.  There are many air pollutants that have a significant, quantifiable impact on human health.  These include nitrogen oxides, sulfur oxides, and small particles known as PM2.5. 

The study simulated levels of air pollution across the United States under various scenarios of adoption of EVs and the use of renewable energy.  The simulations clearly showed that the combination of widespread use of electric vehicles and the greening of the power grid would result in huge cumulative public health benefits.  But these benefits will take time to accrue.  The internal combustion vehicles being sold today will still be on the roads for many years and will continue to spread pollution everywhere there are roads.

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New research reveals how large-scale adoption of electric vehicles can improve air quality and human health

Photo, posted May 7, 2020, courtesy of Mark Vletter via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Reducing emissions from cement

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Cement production accounts for about 7% of global carbon emissions.  It is one of the most difficult challenges for emissions reduction.  The emissions associated with producing cement come from both the energy used to provide heat for the process and from the chemical reactions that take place in the formation of cement.  Cement is an essential building block of society, and its use is not expected to decline over time.

A German company called Heidelberg Materials is embarking on an ambitious project to reduce carbon emissions from a cement plant in Norway.  They are building a facility to use absorbent chemicals to capture large quantities of carbon dioxide emitted through cement production.  More than half a ton of carbon dioxide arises from every ton of cement produced at the plant.

Once the carbon dioxide is captured it will be chilled to a liquid, loaded onto ships, and carried to a terminal farther up the Norwegian coast.  From there, it will be pumped into undersea rocks located 70 miles offshore and a mile and a half below the bottom of the North Sea.

With all of this complicated process going on, cement from the plant is likely to be quite expensive.  It might even be two or three times the price of ordinary cement.  Heidelberg Materials is counting on customers’ willingness to pay much more for cement that comes with green credentials. 

Can this be economically viable?  Heidelberg estimates that cement accounts for only about 2% of the cost of a large building project but as much as 50% of the emissions.  As a result, using carbon-free cement could be a relatively inexpensive way for builders to reduce emissions.

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Cement Is a Big Polluter. A Plant in Norway Hopes to Clean It Up.

Photo, posted May 7, 2016, courtesy of Phillip Pessar via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Ocean geoengineering

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As greenhouse gas emissions continue to be dangerously large and the perils of climate change are increasingly apparent, the world is increasingly exploring ways to deliberately intervene in climate systems.  A number of these ideas involve introducing substances into the atmosphere, but there are also ways to tinker with the oceans.

The oceans naturally absorb about a third of the carbon dioxide that humans pump into the atmosphere, mostly by burning coal, gas, and oil.  People are exploring ways to get the ocean to take up even more of the carbon dioxide.  One approach that is gaining traction is known as alkalinity enhancement.  By adding limestone, magnesium oxide, or other alkaline substances to rivers and oceans, it changes their chemistry and makes them soak up more carbon dioxide.

This approach has been around for a while as a way to mitigate acid rain in rivers and has been very successful.  A start-up company in Canada called CarbonRun is building a machine that grinds up limestone and will release the powder it produces into a local river in Nova Scotia.  The limestone in the river will be naturally converted into a stable molecule that will eventually be washed into the seas, where it should remain for thousands of years.

Expanding this approach to oceans faces many challenges including the costs and complexities of obtaining, processing, and transporting vast amounts of limestone to where it is to be released.  There are also potential environmental issues to grapple with.  But CarbonRun and others are moving forward with testing the approach.

In any event, the biggest barrier to ocean alkalinity enhancement is proving that it works.  That effort is underway.

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They’ve Got a Plan to Fight Global Warming. It Could Alter the Oceans.

Photo, posted May 27, 2007, courtesy of John Loo via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Rising methane emissions

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Methane is a colorless and odorless gas that occurs abundantly in nature and is also a product of certain human activities.  It’s a short-lived but highly potent greenhouse gas and, as a result, is a major driver of climate change.  In fact, methane heats the atmosphere nearly 90 times faster than carbon dioxide over a 20-year period. 

Despite a global pledge from more than 150 nations to reduce methane emissions by 30% this decade, methane emissions continue to rise.  In fact, according to a new paper led by researchers from Stanford University, total annual methane emissions have increased 20% over the past two decades. 

The paper, which was recently published in the journal Environmental Research Letters, found that atmospheric concentrations of methane today are more than 2.6 times higher than in pre-industrial times.  In fact, atmospheric methane concentrations are currently the highest they’ve been in at least 800,000 years.

Methane emissions from coal mining, oil and gas production and use, cattle and sheep ranching, and decomposing organic waste in landfills are responsible for driving the growth.  In 2020, the most recent year for which data was available, nearly 400 million tons – or about two-thirds – of global methane emissions came directly from human activities. 

Methane concentrations in Earth’s atmosphere have increased at record speed over the past five years.  According to the research team, only the European Union and possibly Australia seem to have decreased methane emissions from human activities over the past two decades.  This trend “cannot continue if we are to maintain a habitable climate.”

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Methane emissions are rising faster than ever

Photo, posted December 4, 2010, courtesy of Dani Mettler via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

The impact of climate change on agriculture

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Agriculture is a major part of the climate problem and remains one of the hardest human activities to decarbonize.  Agriculture is responsible for approximately 30% of global greenhouse gas emissions.

On farms around the world, excess fertilizer gets broken down by microbes in the soil, releasing nitrous oxide into the atmosphere.  Nitrous oxide is a greenhouse gas that is 300 times more potent than carbon dioxide.

According to a sweeping global research review recently published in the journal Science, greenhouse gas emissions from agriculture are now 18 times higher than they were in the 1960s. 

The research, which was co-written by professors at the University of Minnesota with more than 20 experts around the world, also reveals the likelihood of an emergent feedback loop between climate and agriculture.  As the changing climate puts more pressure on the global food supply, agriculture will, out of necessity, adopt practices that may exacerbate its environmental impact. Without changes in agriculture, this feedback loop could make it impossible to achieve the Paris Climate Agreement goal of limiting global warming to 1.5 degrees Celsius above pre-industrial levels. 

The research identifies several agricultural practices that could improve efficiency and stabilize our food supply in the decades to come, including precision farming, perennial crop integration, agrivoltaics, nitrogen fixation, and novel genome editing. 

Finding ways to reduce the warming impact of agriculture while maintaining high crop yields are essential to both mitigating climate change and protecting our food supply from its impacts.

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Impact of Climate Change on Agriculture Suggests Even Greater Challenges to the Environment, Global Food Supply and Public Health

Photo, posted October 16, 2010, courtesy of Timlewisnm via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Canadian wildfires and global emissions

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The wildfires that burned vast amounts of Canada’s boreal forests in 2023 produced enormous amounts of smoke that found its way into American cities, working its way down the eastern seaboard and even producing unsafe air in Florida.

Researchers at Cal Tech and the Jet Propulsion Laboratory analyzed the carbon emissions associated with these fires last year and found that they were greater than those of all but three countries:  China, the US, and India.

Boreal forests have historically been a natural defense against climate change by storing carbon in trees rather than adding carbon dioxide to the atmosphere.  The fires in Canada, fueled by hot and dry weather, were extraordinary when compared with historical records.  But such fires are likely to be increasingly common as the climate continues to warm.

However, the hot and dry weather that fueled the 2023 fires was exceptional in many ways, involving early snow melt and so-called flash droughts.  This year’s fires in Canada are still bigger than average, but so far have not been as destructive as last year’s. 

Canada has been warming at about twice the global rate.  The extreme temperatures last summer were a major factor in the fueling of the fires, which burned an area almost the size of Florida.

Forests absorb about a quarter of global carbon emissions, but the increasing frequency and intensity of fires are calling into question their ability to continue to do so.  Parts of the Canadian forests are not regrowing after fires as they have in the past, partly because blazes burn trees so frequently and intensely.

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Canada’s Wildfires Were a Top Global Emitter Last Year, Study Says

Photo, posted June 8, 2023, courtesy of the Metropolitan Transportation Authority via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Ecofriendly Glass

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Glass has been used for thousands of years to make everything from windows to bottles to microscope slides.  For all that time, most glass has been in the form of soda lime silicate glass, which is made by melting quartz sand with carbon-based ingredients – soda ash and limestone – at high melting temperatures of about 2600 degrees Fahrenheit.

The process results in substantial carbon emissions.  Worldwide, glass manufacturing produces over 86 million tons of carbon dioxide per year.  Most of that comes from burning fuel to reach the high temperatures needed to make the glass, but about a quarter of it comes from the decomposition of the carbon-based materials used.

Researchers at Penn State University have developed an entirely new type of glass that represents an alternative to soda lime glass.  The glass – that they call LionGlass – eliminates the use of carbonate batch materials and has a melting temperature 700 degrees lower than traditional glass.   The new material has the potential to cut the carbon footprint of glass manufacturing in half.  It is also 10 times more crack-resistant than ordinary glass, which would enable light weighting of glass products, lowering the emissions associated with transporting glass and glass products.

Recently, Penn state has entered into a partnership with the Italian company Bormioli, one of the world’s leading glass manufacturers that specializes in high-end packaging for fragrances, cosmetics, and tableware.  By focusing on a smaller, high-end market, the focus can be on fine-tuning the glass and determining the feasibility of scaling it up further for other uses.

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Ecofriendly glass invented at Penn State secures partner for product development

Photo, posted December 26, 2005, courtesy of Lachlan Hardy via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Solar farms and pollinators

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Two important environmental challenges are finding some literal common ground:  the need to reduce carbon emissions and the fight to stave off global biodiversity collapse.  Both issues can be addressed at solar farms.

Solar energy is an important weapon in the battle against climate change.  But utility-scale solar farms take up large amounts of land.  Large-scale solar farms already take up nearly a thousand square miles of land in the US and will take up much more in the coming decades.

In the meantime, the biodiversity collapse is being driven in large part by habitat loss.

Given all this, solar farm operators, biologists, and environmentalists are teaming up to grow pollinator-friendly plants in and around solar farms. The plantings attract insects, birds and even mammals. The more plant diversity in the solar farms, the more environmental benefits can be achieved. 

There are costs associated with creating pollinator-friendly solar farms. Ideally, solar panels need to be installed at greater height than otherwise in order to permit growing many of the plants that attract bees and butterflies.  But there are economic benefits associated with attracting and sustaining pollinators.  On a cautionary note, there have already been cases of greenwashing, where solar operators claim environmental benefits far in excess of the scope of the actual efforts they have made. 

There are both governmental and non-governmental agencies seeking to assess and certify pollinator-friendly solar farms.  There is considerable variability in the ecological value of existing farms.  Pollinator-friendly solar farms are in their early days, but they have a lot to offer as a win-win strategy for the environment.

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Solar Farms Have a Superpower Beyond Clean Energy

Photo, posted December 4, 2014, courtesy of Juwi Renewable Energies Limited via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

An electric reactor for industry

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The industrial sector accounts for nearly a third of greenhouse gas emissions in the US, which is more than the annual emissions from cars, trucks, and airplanes combined.  These emissions primarily come from burning fossil fuels to produce goods from raw materials as well as from the chemical reactions associated with production.  Many industrial processes require very high temperatures that are not easily achieved other than by burning fossil fuels.

Researchers at Stanford University have developed and demonstrated a new kind of thermochemical reactor that can generate the huge amounts of heat required for many industrial processes that runs on electricity rather than the burning of fossil fuels.  The researchers claim that the design is also smaller, cheaper, and more efficient than the fossil fuel technology it would replace.

Standard industrial thermochemical reactors burn fossil fuel to heat a fluid that is piped into the reactor, much like the way home radiators work, albeit at far higher temperatures.  The new reactor uses magnetic induction, similar to the way that induction cooktops work.  Heat is transferred by inducing a current into materials that heat up as the current flows.

A proof-of-concept demonstration powered a chemical reaction called the reverse water gas shift reaction and resulted in more than 85% efficiency.  The reaction in question converts carbon dioxide into a valuable gas that can be used to create sustainable fuels. 

The Stanford researchers are working to scale up their new reactor technology and expand its potential applications.  They are working on designs for reactors for capturing carbon dioxide and for manufacturing cement. 

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Electric reactor could cut industrial emissions

Photo, posted October 30, 2022, courtesy of Helmut via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

A better way to produce green hydrogen

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Hydrogen has great potential as a fuel and an energy carrier for many applications.  Burning it or consuming it in fuel cells does not produce carbon emissions.  As a result, there has long been the vision for a future hydrogen economy.  Whether the hydrogen economy would ever come about given how various other technologies have evolved over time is questionable.  But regardless, hydrogen is valuable for many industrial and commercial applications including the manufacture of ammonia and the refining of metals.

Hydrogen is produced in industrial quantities from natural gas by a carbon-dioxide-producing process known as methane-steam reforming.  To take its place as a green energy source, hydrogen needs to be produced by splitting water into its constituent oxygen and hydrogen components by the process of electrolysis. 

The problem is economic.  Methane-steam reforming produces hydrogen at a cost of about $1.50 per kilogram.  Green hydrogen costs about $5 a kilogram.

Researchers at Oregon State University have developed a new photocatalyst that enables the high-speed, high-efficiency production of hydrogen.  The material, called RTTA, is a metal organic framework containing ruthenium oxide and titanium oxide.  Ruthenium oxide is expensive, but very little is needed.  For industrial applications, if the catalyst shows good stability and reproducibility, the cost of the small amount of this exotic material becomes less important.

The photocatalyst, when exposed to sunlight, quickly and efficiently splits water yielding hydrogen.  The Oregon State discovery has real potential.

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Oregon State University research uncovers better way to produce green hydrogen

Photo, posted July 7, 2023, courtesy of Bill Abbott via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Less coal for making steel

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Steel is primarily produced using one of two methods:  blast furnaces or electric arc furnaces.  The first blast furnaces were built in the 14th century.  Making steel in a blast furnace starts by melting the raw materials of iron ore, limestone, and coal at very high temperatures.  The resultant reactions ultimately lead to two products:  iron saturated with carbon and carbon dioxide.  A second furnace reacts the liquid iron with oxygen to remove the carbon and results in steel along with even more carbon dioxide.

Making steel using an electric arc furnace is considerably less emissions-intensive and more sustainable.  So-called circular steel making powered by electric arc furnaces uses electricity to melt scrap and other input materials and turn them into high-quality steel.  Of course, to really minimize the emissions associated with steelmaking, the arc furnaces need to get their power from renewable energy sources. 

The global steel industry is turning away from polluting coal-fired blast furnaces and towards electric arc furnaces, which now account for roughly half of all planned new steelmaking capacity. This represents real progress towards a green steel transition.

By the end of this decade, electric arc furnaces will account for more than a third of steelmaking.  However, there are still plenty of new coal-based steel furnaces being built.  So even as electric arc furnaces account for a greater share of steelmaking, these new coal furnaces will still drive emissions upward.   Environmental advocates argue that what the steel industry needs is to make clean development a true priority and back away from coal-based developments.

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Steelmakers Increasingly Forgoing Coal, Building Electric

Photo, posted July 16, 2018, courtesy of Daniel Steelman via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Emissions and the Great Salt Lake

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The Great Salt Lake in Utah has been described as a puddle of its former self.  The lake’s size fluctuates naturally with seasonal and long-term weather patterns, but the lake has been experiencing decline for decades as Utahans take water out of the rivers and streams that once fed the lake.  Over recent decades, the lake has lost 73% of its water and 60% of its surface area.

For years, scientists and environmental leaders have warned that the Great Salt Lake is headed toward a catastrophic decline.  Recent research has found that the lake’s desiccating shores are becoming a significant source of greenhouse gas emissions.  Scientists have calculated that the dried-out portions of the lakebed released about 4.1 million tons of carbon dioxide and other greenhouse gases in 2020.

The recent study, published in the journal One Earth, suggests that the Great Salt Lake – which is largest saltwater lake in the Western Hemisphere – as well as other shrinking saline lakes around the world could become major contributors of climate-warming emissions.

The shrinking back of the water has exposed a dusty lakebed that is laced with arsenic, mercury, lead, and other toxic substances.  Some are naturally occurring, and others are the residue of mining activity in the region.  These substances threaten to increase rates of respiratory conditions, heart and lung disease, and cancers.

As the lake shrinks, it is becoming saltier and uninhabitable to native flies and brine shrimp and may increasingly become unable to support the 10 million migratory birds and wildlife that frequent it.

The new research about greenhouse gas emissions just adds to a dire list of environmental consequences brought on by the lake’s steep decline.

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Shrinking Great Salt Lake Becoming Source of Heat-Trapping Gas

Photo, posted January 20, 2020, courtesy of Matthew Dillon via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Better wood for storing carbon

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Scientists have discovered a new type of wood that is highly efficient at storing carbon.  A comprehensive survey of the microscopic structure of the wood from many species of trees revealed that there is a type of wood that is neither softwood, such as pine and conifers, or hardwood, such as oak, ash, and birch.

The scientists from Cambridge University and Jagiellonian University in Poland analyzed some of the world’s most iconic trees using electron microscopy to survey their microscopic structure.

They found that tulip trees, which are related to magnolias and can grow over 100 feet tall, have a unique type of wood.  The trees, which diverged from magnolias far back to a time when atmospheric CO2 concentrations were low, grow very tall and very quickly.  These features were an adaptation to those conditions and result in the ability to store larger concentrations of carbon to compensate based on their microstructure.  The elementary units of wood are known as macrofibrils, and tulip trees have much larger macrofibrils than hardwoods but smaller than those of softwoods.  This unusual intermediate structure makes the trees highly effective at carbon storage.

Based on the research, it may be the case that tulip trees will end up being useful for carbon capture plantations – tree plantings specifically for the purpose of mitigating the effects of climate change.  Some east Asian countries are already using various tulip tree species in plantations for locking in carbon.  This was based on their large size and rapid growth, but it turns out that their novel wood structure may be the most compelling reason to use them.

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Scientists discover entirely new wood type that could be highly efficient at carbon storage

Photo, posted March 3, 2021, courtesy of Thomas Quine via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Wildfires and carbon storage

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Forests are known to be a key natural solution to the increasing amounts of carbon dioxide in the atmosphere.  For this reason, there are widespread efforts to plant more trees around the world and to prevent increasing deforestation for development and agriculture.  But a new study has highlighted the fact that wildfires in the western US are degrading the potential for forests to help curb climate change.

The study has established a baseline for how much carbon is currently stored in Western forests, how that amount is changing, and how fires and droughts are affecting the ability of the forests to mitigate climate change.

The study made use of survey data collected by the US Forest Service to estimate how much carbon is stored in 19 ecoregions across the West.  These ecoregions range from hot and dry areas in the Southwest to the wet and cool regions of the Pacific Northwest.

The study reveals that the carbon stored in living trees declined across much of the Western US between 2005 and 2019.  Carbon stored in dead trees and woody debris increased.  These things do not provide long-term carbon storage.  Instead, they release it back into the atmosphere through decomposition or combustion in forest fires.

The increasing frequency and intensity of wildfires, especially since 2020, indicate that the decline in live carbon stored in the forests will become increasingly pronounced.  The result, according to the study’s authors, is that we cannot rely on increasing carbon storage in Western US forests.  It may be possible to increase the stability of carbon storage in the forests with mechanical thinning and prescribed burning, but the carbon carrying capacity of those forests is not likely to be what is needed.

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Forest carbon storage has declined across much of the Western US, likely due to drought and fire

Photo, posted July 25, 2021, courtesy of Felton Davis via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Thawing permafrost:  Is it a ticking timebomb?

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Permafrost covers about a quarter of the landmass in the Northern Hemisphere.  It stores vast quantities of organic carbon in the form of dead plant matter.  As long as it stays frozen, it is no threat to the climate.  But as it thaws, microorganisms start breaking down that plant matter and large amounts of carbon are released into the atmosphere in the form of carbon dioxide and methane.

This process has often been described as a ticking timebomb for the climate.  The theory is that once global warming reaches a certain level, the process will become self-amplifying setting off a catastrophic amount of warming.  If that level was reached, it would be a tipping point in the changing climate.

An international research team from the Alfred Wegener Institute in Germany has extensively researched this hypothesis.  Their conclusion is that within the permafrost, there are multiple geological, hydrological, and physical processes that are self-amplifying and, in some cases, irreversible.  However, these processes act only locally or regionally.  There is no evidence that some particular threshold in global warming could affect all permafrost and accelerate its thawing on a global level.

This research does not mean that Arctic permafrost is nothing to worry about.  In fact, there are ways in which it is more worrisome.  Because the permafrost is very heterogenous – meaning it is very different in different places – there will be numerous small, local tipping points that will be exceeded at different times and at different levels of warming.  All of this will proceed in step with global warming, contributing to the overall worsening situation.  There is no warming level below which permafrost thawing is not a problem.

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Thawing permafrost: Not a climate tipping element, but nevertheless far-reaching impacts

Photo, posted January 24, 2014, courtesy of Brandt Meixell / USGS via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Benefits of electric school buses

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There are about half a million school buses in use in the U.S.  A large number of them are older, highly polluting diesel buses.  There are well-established health and climate benefits of switching from diesel vehicles to electric vehicles but making the switch is expensive.  Diesel buses generally cost between $65,000 to $120,000, depending on the type and configuration.  Electric buses cost about $250,000 each.

The substantial cost makes it a difficult decision for local, state, and federal officials, particularly since the actual magnitude of the benefits is not well known.

A new study by researchers at Harvard’s T.H. Chan School of Public Health has quantified these benefits.  According to the study, replacing each bus may yield up to $247,600 in climate and health benefits. These benefits derive from fewer greenhouse gas emissions and from reduced rates of adult mortality and childhood asthma. 

The study compared the amounts of carbon dioxide emitted from diesel bus tailpipes to the emissions associated with generating electricity for the buses and producing their batteries.  It also compared how these respective emissions contribute to fine particulate air pollution, which is linked to adult mortality and the onset of childhood asthma.  The study concluded that particularly in dense urban settings, the savings incurred from electrifying older school buses easily outweigh the costs of replacing them.

An important question not tackled in the study is how electric school buses impact children’s exposure to in-cabin air pollution while riding the bus.  This issue could further inform policy decisions.

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Electric school buses may yield significant health and climate benefits, cost savings

Photo, posted May 9, 2008, courtesy of Christine H. via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Record carbon dioxide levels

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Despite the increasing concern about the warming climate, the period between March of last year and March of this year has set a new record for the largest 12-month gain in atmospheric CO2 concentration ever observed.  The new level, measured at Hawaii’s Mauna Loa Observatory was nearly 5 parts per million higher than last year’s level reaching more than 426 parts per million.

CO2 levels averaged 280 ppm for the past 800,000 years until the Industrial Revolution began and people started burning fossil fuels.  Levels started being measured at Mauna Loa in 1958, when they were 315 ppm.  Between 1958 and 2005, the CO2 level rose to 380 ppm.  Over the past 19 years, the amount of CO2 has continued to rise rapidly and with it, global temperatures.

The record increase in carbon dioxide over this past year is probably associated with the end of an El Niño event.  The previous record increase in 2015-2016 was also associated with El Niño.

But the overall trend is clear and discouraging.  Over the past 66 years, the amount of carbon dioxide in the atmosphere has increased by 35%.  This increase is a result of the burning of coal, oil, and natural gas, as well as the effects of deforestation and livestock agriculture.

Carbon dioxide absorbs heat radiating from the Earth’s surface and re-releases it in all directions, including back toward Earth’s surface.  Without this greenhouse effect, the Earth would actually be frozen.  But people are supercharging the natural greenhouse effect and causing the global temperature to rise.  Global energy demand continues to grow and if we continue to meet that demand mostly with fossil fuels, temperatures will continue to rise.

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Scripps Institution of Oceanography: CO2 levels have largest 12-month gain

Photo, posted March 3, 2014, courtesy of Jon Roig via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

Recycling cement

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Concrete is the second-most-used material on the planet.  Only water is used more.  Producing concrete is responsible for 7.5% of human-produced carbon dioxide emissions.  So, finding a cost-effective way to reduce these emissions is a major challenge in the face of ever-growing global demand for concrete.

Researchers at Cambridge University have found that used cement is an effective substitute for lime flux, which is an essential material used in steel recycling that results in a waste product called slag.  When lime is replaced with used cement, the end product instead is recycled cement that can be used to make new concrete.

The process does not add any significant costs to concrete or steel production and significantly reduces the emissions associated with both.

Concrete is made from sand, gravel, water, and cement.  Cement is made by a process called clinkering, in which limestone and other materials are heated to 2,600 degrees Fahrenheit.  The process converts the materials into cement but releases large amounts of CO2 as limestone decarbonates into lime. 

Cambridge researchers found that using cement clinker and iron oxide instead of lime works well in steel recycling.  Crushing old concrete and taking out the sand and stone results in a cement that is reactivated by the recycling furnace to produce a material with excellent properties. 

Recent tests by the Materials Processing Institute showed that recycled cement can be produced at scale in an electric arc furnace.  Ultimately, this method could produce zero emission cement if the electricity for the furnace comes from renewable sources.

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Cement recycling method could help solve one of the world’s biggest climate challenges

Photo, posted July 18, 2011, courtesy of Kenta Mabuchi via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

The largest carbon removal plant

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Direct air capture (DAC) is process that removes carbon dioxide out of the air and stores it away where it can no longer trap heat in the atmosphere.  It is intended to be a way of getting rid of the greenhouse gases that have built up in the atmosphere.  In principle, it’s a great idea.  In practice, it is a huge challenge.

In 2017, a company called Climeworks became the first company to take carbon dioxide out of the air and sell it as a product for use in carbonated drinks and in greenhouses.  In 2021, the company opened a DAC plant called Orca in Iceland that captures CO2 and permanently stores it underground.  Clients like Microsoft pay Climeworks for doing this as a way of offsetting their own emissions.

Recently, Climeworks has started operating a new plant called Mammoth – also in Iceland – that will be able to capture about 10 times more carbon dioxide than Orca.  Iceland is a prime location for DAC technology because its abundant geothermal energy makes powering it cheap and environmentally friendly.

Mammoth, when fully operational, will remove about 36,000 tons of carbon dioxide a year, the largest DAC system in the world.  But there is a long, long way to go.  Microsoft alone emits nearly 13 million tons of carbon dioxide a year.

There are multiple DAC projects in development including several in the United States being funded by the Bipartisan Infrastructure Law.  The four DAC hubs being developed under the program are each supposed to have the capacity to capture at least a million metric tons of CO2 a year.

Whether DAC can make a real difference remains to be seen.

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The world’s largest carbon removal plant is here, and bigger ones are on the way

Photo credit: Climeworks

Earth Wise is a production of WAMC Northeast Public Radio

WAMC Northeast Public Radio

WAMC/Northeast Public Radio is a regional public radio network serving parts of seven northeastern states (more...)